基于广义相对安全率的空间变异土坡稳定可靠度设计控制标准与方法

岩土工程可靠度设计方法已被正式纳入国际标准《结构可靠性总原则ISO2394：2015》，成为下一代岩土工程设计规范发展的必然趋势。我国土坡稳定设计规范仍以确定性设计方法为主，无法合理地考虑土体空间变异性等不确定性因素。土体空间变异性显著影响土坡稳定可靠度和破坏模式，是建立有效的土坡稳定可靠度控制标准和设计方法的关键难点。本项目拟开展考虑空间变异性的土坡稳定可靠度控制标准和设计方法研究，提出具有普适性的土坡稳定安全性和可靠性二元控制指标—广义相对安全率，突破传统相对安全率在概率分布类型和计算方法上的局限。在此基础上，提出考虑空间变异性的土坡稳定性目标可靠度校准方法，建立基于设计响应面的土坡稳定高效全概率设计方法和近似概率极限状态设计方法，发展变化设计条件下土坡稳定可靠度设计高效更新方法。研究成果将推动岩土工程可靠度设计理论的进一步发展，为制定我国土坡稳定可靠度设计规范提供理论依据和技术支撑。

Geotechnical reliability-based design (RBD) has been officially coded in the new version of “General Principles on Reliability for Structures ISO 2394: 2015”. This indicates that it is a mandatory trend that RBD will be adopted in the next generation of geotechnical design codes. However, soil slope stability design in China has been using deterministic design methods, for which various uncertainties in slope engineering (particularly spatial variability of soils) cannot be, rationally, taken into account. Spatial variability of soils affects the reliability and failure modes of slope stability, and it is one of the major difficulties in developing effective reliability control criterion and RBD methods for soil slope stability design. This project focuses on target reliability calibration and design methods of soil slope stability considering spatial variability. It proposes a unified measure of the safety and reliability of soil slope stability, namely generalized ratio of safety margin, which allows the ratio of safety margin to be calculated using any types of probability distributions and calculation methods. Based on the generalized ratio of safety margin, a target reliability calibration method is proposed with consideration of spatial variability. Then, design response surface is used to develop an efficient full probabilistic design method and semi-probabilistic limit state design method for soil slope stability design, and an efficient RBD updating method is also proposed for various design situations. Research outcomes of this project not only lead to further theoretical advances in geotechnical RBD, but also lay out solid grounds and technical supports to RBD codification for soil slope stability design in China.